1. Field
The present invention relates to the field of input control devices. More specifically, it relates to force-sensitive input-control devices with multiple surfaces capable of providing intuitive input in up to six degrees of freedom, including position and rotation relative to three axes. Six dimensions of input can be generated without requiring movement of the controller, which provides a controller suitable for controlling both cursors or display objects in an interactive computer system. Further, the controller in insensitive to acoustic or electromagnetic noise and is thus suitable for controlling equipment such as heavy cranes and fork lift trucks.
2. Art Background
2. (a) Prior art 3D and 6D input control devices
Two-dimensional input control devices such as mice, joysticks, trackballs, light pens and tablets are commonly used for interactive computer graphics. These devices are refined, accurate and easy to use. Three-dimensional ("3D") devices allow for the positioning of cursors or objects relative to conventional X, Y and Z coordinates. Six-dimensional ("6D") devices are capable of also orienting or rotating objects. More specifically, 6D devices may provide position information as in a 3D device and further provide rotational control about each of three axes, commonly referred to as roll, pitch and yaw. However, current 3D and 6D input devices do not exhibit the refinement, accuracy or ease of use characteristic of existing 2D input devices. In fact, existing 3D/6D input devices are typically cumbersome, inaccurate, non-intuitive, tiring to use, and limited in their ability to manipulate objects.
One well known category of 3D computer controllers are the "computer gloves," such as the Power Glove controller distributed by Mattel, Inc. Similar devices include the Exos Dextrous Hand Master by Exos, Inc., and the Data Glove by VPL Research, Inc. These controllers are worn as a glove and variously include sensors for determining the position and orientation of the glove and the bend of the various fingers. Position and orientation information is provided by ranging information between multiple electromagnetic or acoustic transducers on a base unit and corresponding sensors on the glove. However, the user is required to wear a bulky and awkward glove and movement of these awkward controllers in free space is tiring. Further, these devices are typically affected by electromagnetic or acoustic interference, and they are limited in their ability to manipulate objects because of the inherent.
A second category of 3D/6D controllers are referred to as "Flying Mice." The Bird controller by Ascension Technology Corp. of Burlington, Vt. tracks position and orientation in six-dimensions using pulsed (DC) magnetic fields. However, it is affected by the presence of metals and also requires manipulating the controller in free space. The 2D/6D Mouse of Logitech Inc. is similar in function, but uses acoustic ranging similar to the Mattel device. The 3SPACE sensor from Polhemus, described in U.S. Pat. No. 4,017,858, issued to Jack Kuipers Apr. 12, 1977, uses electromagnetic coupling between three transmitter antennas and three receiver antennas. Three transmitter antenna coils are orthogonally arranged as are three receiver antennas, and the nine transmitter/receiver combinations provide three dimensional position and orientation information. However, all "flying mouse" devices require the undesirable and tiring movement of the user's entire arm to manipulate the controller in free space. Further, these devices are either tethered by a cord or sensitive to either electromagnetic or acoustic noise.
A device similar to the flying mice is taught in U.S. Pat. No. 4,839,838. This device is a 6D controller using 6 independent accelerometers in an "inertial mouse." However, the device must still be moved in space, and the use of accelerometers rather than ranging devices limits the accuracy. Another inertial mouse system is taught in U.S. Pat. No. 4,787,051 issued to Lynn T. Olson. A third category of 3D/6D controllers 3D/6D joysticks and trackballs. Spaceball of Spatial Systems, Inc. is a rigid sphere containing strain gauges or optical sensors to measure the forces and torques applied to a motionless ball. The user pushes, pulls or twists the ball to generate 3D translation and orientation control signals. Spaceball is described in detail in U.S. Pat. No. 4,811,608 issued to John A. Hilton Mar. 14, 1989. Similarly, the DIMENSION 6/Geoball controller distributed by CiS Graphics Inc. incorporates a 6-axis optical torque sensor housed in a spherical enclosure. The device measures translational forces and rotational torques. However, these devices are subject to a number of disadvantages. For example, it is difficult to provide for precise positioning, as there is no provision for the use of a stylus. Further, these devices are primarily controlled with hand muscles, rather than with the more precise finger muscles. Further still, these devices provide for only relative control and have no provision for providing an absolute origins or an absolute positions. They are therefor not suitable for providing closure in digitized 3 D inputs. Finally, they are limited in there ability to provide an intuitive feel for 3D manipulation of a controlled object not specified in the Cartesian coordinate system. For example, they are not readily adaptable to spherical or cylindrical coordinate systems.
2. (b) Prior art force-sensitive transducers
Force-sensitive transducers are characterized in that they do not require a significant amount of motion in order to provide a control input. These devices have appeared in a number of configurations, some of which are capable of sensing not only the presence or non-presence of the touch of a user's finger or stylus, but also the ability to quantitatively measure the amount of force applied. One such a device is available from Tekscan, Inc. of Boston, Mass. This device includes several force-sensitive pads in a grid-based matrix that can detect the force and position of multiple fingers at one time. Another force-sensitive device is available from Intelligent Computer Music Systems, Inc. of Albany, N.Y. under the TouchSurface trademark. The TouchSurface device can continuously follow the movement and pressure of a fingertip or stylus on its surface by responding to the position (X and Y) at which the surface is touched and to the force (Z) with which it is touched. Further, if two positions are touched simultaneously in the TouchSurface device, an average position of the two positions is provided. However, these devices are currently limited in manipulating objects beyond 2.5 dimensions, i.e. X-position, Y-position, and positive Z-direction, and are not available in any intuitive controllers.
Force-sensitive transducers have been used in two-dimensional applications in place of spring-loaded joysticks. For example, U.S. Pat. No. 4,719,538 issued to John D. Cox teaches using the force-responsive capacitive-transducers in a joystick-type device. However, these devices do not typically provide for 3D/6D inputs. An augmented 2D controller using force-sensitive devices is taught in U.S. Pat. No. 4,896,543 issued to Larry S. Gullman. Gullman describes a three-axis force measurement stylus used as a computer input device wherein the forces sensed by the stylus are used for recognizing ciphers, selecting colors, or establishing line widths and line densities. However, this device does not provide inputs for roll, yaw or pitch, and does not provide any input for a negative Z input (i.e. there is no input once the stylus is lifted). Thus, it is limited in its ability to provide 3D positioning information, as this would require an undesirable bias of some sort.
2. (c) Prior art 3D/6D field controllers
3D/6D controllers are found in many field applications, such as controllers for heavy equipment. These devices must be rugged, accurate and immune from the affects of noise. Accordingly, many input control devices used for interactive computer graphics are not suitable for use in field applications. As a result, heavy equipment controllers typically consist of a baffling array of heavy-but-reliable levers which have little if any intuitive relationship to the function being performed. For example, a typical heavy crane includes separate lever controls for boom rotation (swing), boom telescope (extension), boom lift and hook hoist. This poor user interface requires the operator to select and select and pull one of a number of levers corresponding to the boom rotation control to cause the boom to rotate to the left. Such non-intuitive controls makes training difficult and accidents more likely.
Accordingly, it is desirable to provide a 3D/6D controller that is easy to use, inexpensive, accurate, intuitive, not sensitive to electromagnetic or acoustic interference, and flexible in its ability to manipulate objects. Specifically, a substantial need exists for a graphical input device capable of providing for the precision manipulation of position and spatial orientation of an object, and that also provides for precise positioning and orientation by the use of a stylus or pen. It is desirable that the device accepts intuitive and simple input actions such as finger motion to manipulate position and orientation. It is desirable that it does not require manipulation of a controller in free space or otherwise cause fatigue. It is desirable that the device provides the dual-functionality of both absolute and relative inputs, that is, inputs similar to a data tablet or touch panel that provide for absolute origins and positions, and inputs similar to mice and trackballs that report changes from former positions and orientations. It is desirable that the device recognizes multiple points for positioning and spatial orientation and allows the use of multiple finger touch to point or move a controlled object in a precise manner. Further, it is desirable to have a controller which exhibits a zero neutral force, that is, one that does not require a force on the controller to maintain a neutral position.